METHOD OF FLOATING CALCIUM CARBONATE ORE AND FLOTATION REAGENT THEREFOR

Abstract: The invention relates to a method of floating calcium carbonate ore containing silicates as impurities. Flotation is performed in the presence of a quaternary ammonium compound and an alkylene oxide adduct of an amine compound, the silicate being concentrated in the float.

Description: METHOD OF FLOATING CALCIUM CARBONATE ORE AND FLOTATION REAGENT THEREFOR The present invention relates to a method of float¬ ing calcium carbonate ore containing silicates as impu¬ rities. According to the invention, flotation is perfor¬ med in the presence of a quaternary ammonium compound and an alkylene oxide adduct of an amine compound, the silicate being concentrated in the float. From US Patent Specification 4,995,965 it is known to separate calcium carbonate from impurities, such as silicate, by the steps of floating the silicate and con- centrating the valuable mineral, i.e. the calcium car¬ bonate in the remainder, in the presence of amine-group- containing collectors. From this patent specification appears that a number of cationic compounds, such as methyl-bis (2-hydroxypropyl) -cocoalkyl ammonium methyl sulphate, dimethyl didecyl ammonium chloride, di ethyl- di (2-ethylhexyl) -ammonium chloride, dimethyl- (2-ethyl- hexyl)-cocoalkyl ammonium chloride, dicocoalkyl dimethyl ammonium chloride, and n-tallow alkyl-1, 3-diamino pro¬ pane diacetate can be used as collectors in such a flo- tation procedure. The patent specification also states that quaternary ammonium compounds, as represented by Arquad 2C (dimethyl dicocoalkyl ammonium chloride) and a combination of Duomac T (N-tallow alkyl-1,3-diamino propane diacetate) and Ethomeen 18/16 (long-chain alkylamine + 50 EO) can be used as collectors, although they yield an unacceptably high content of acid-inso¬ luble matter in the valuable mineral. It has now surprisingly been found that when clea¬ ning calcium carbonate containing silicates as impurity, a very high yield and/or high selectivity (low content of acid-insoluble matter) can be achieved if reverse flotation is performed in the presence of a quaternary ammonium compound in combination with an alkylene oxide adduct of an amine compound. More specifically, the present invention relates to a f oth-flotation process perfomed in the presence of a quaternary ammonium com- pound having the formula Rl + R3 . N-"" ' A- (I) R 2 " " R4 wherein one or two of the groups R]_, R 2 , R3 and R4 are a hydrocarbon group having 8-36 carbon atoms and the re¬ maining groups a hydrocarbon group having 1-7 carbon atoms or a hydroxyalkyl group having 2-7 carbon atoms, and A is an anionic counterion, and an alkylene oxide adduct having the formula (A!)n x H (A 2 )n 2 H R5-(^ R6)s N 7 (^3)n 3 H (II) wherein R5 is a hydrocarbon group having 8-22 carbon atoms, A]_, A 2 and A3 are an alkylene oxide group having 2-4 carbon atoms, Rg is an alkylene group having 2-3 carbon atoms, n_, n 2 and n are 3-20 and the sum of all nι_, n 2 and n 3 is 10-40, and s is 0-3; the weight ratio of the quaternary ammonium compound to the alkylene oxide adduct being 3:2-11:1, preferably 7:3-9:1, and calcium carbonate being recovered from the remainder while contaminating silicates are removed with the float. By the method of the invention, it has now been found possible to significantly reduce the content of insoluble silicates, such as quartz, feldspar, amphibole and pyroxene. In formula (I), two of the groups R]_, R 2 , R3 and R 4 preferably consist of straight or chained, saturated or unsaturated alkyl groups having 8-22, preferably 10-16 carbon atoms, while the two remaining groups preferably are alkyl groups having 1-3 carbon. atoms or hydroxyalkyl groups having 2-3 carbon atoms. A generally is a mo- novalent ion, such as methyl sulphate or chloride. Specific examples of compounds of formula (I) are dimethyl didecyl ammonium chloride, dimethyl dicocoalkyl ammonium chloride, dimethyl dilauryl ammonium chloride, dimethyl distearyl ammonium chloride, dimethyl ditallow alkyl ammonium chloride and corresponding methyl sul¬ phate salts. Alkylene oxide adducts of formula (II) pre¬ ferably are such where R5 is a straight or branched, saturated or unsaturated alkyl group having 10-20 carbon atoms and the sum of all ni, n 2 and n3 is 12-30. Of all the alkyleneoxy groups in the alkylene oxide adduct, 70-100% preferably are ethyleneoxy groups and 0-30% pro- pyleneoxy groups. For reasons of production technique, such compounds are generally preferred where all alkyleneoxy groups are ethyleneoxy groups. The symbol s preferably is 0 or 1. By suitably varying the number of alkyleneoxy groups, their type and the number of carbon atoms in the hydrophobic moiety R, the compounds of for¬ mula (II) can easily be given such properties that they can be mixed with the compounds of formula (I) to form stable mixtures. Moreover, the quaternary ammonium compounds of formula (I) are generally prepared in the presence of an alcoholic solvent, such as isopropanol, in a content of about 10-15% by weight of the ammonium compound. The action of such a solvent usually yields, upon admixture with compounds (I) and (II) , a clear, homogeneous and stable liquid phase. The collectors according to the present invention can be added separately, but are preferably added together as a single flotation reagent. The total con- tent of the two compounds may vary within wide limits but generally amounts to 50-2000, preferably 200-1000 g/tonne of ore to be floated. In the application of the present invention, it is possible, in addition to the additives mentioned above, to add other additives which are well-known in float flotation. Examples of such additives are pH-adjusting agents, such as sodium carbonate and sodium hydroxide; depressants, such as starch, quebracho, tannin, dextrin and guar gum, and polyelectrolytes, such as polyphos- phate and water glass, which have a dispersant effect, often combined with a depressant effect. Other conven¬ tional additives are foaming agents, such as methyl- isobutylcarbinol, triethoxybutane and polypropylene oxide and its alkyl ethers. The method of the invention is further illustrated by the following Example. Example 1 Calcite ore containing 1.6% by weight of silicate mineral (quartz, feldspar, amphibole, pyroxene) was ground in an amount of 0.5 kg together with 0.5 kg of water to a particle size of -250 μm. The ground material was transferred to a 1.5-litre flotation cell. After dilution with water to 1.4 1, 56% of the collector reagent used was added in the form of a 0.5% aqueous solution. After conditioning for three minutes, the float was withdrawn during 1.5 min. Another 22% of the reagent was thereafter added to the remainder, which was conditioned for three minutes, whereupon the whole mix¬ ture was floated for 1.5 min. To the remainder was charged another 22% of the reaction mixture, and the whole mixture was conditioned for 3 min and thereafter floated. The resulting flotation remainder was dried, weighed and analysed for content acid-insoluble in 25% hydrochloric acid. The collectors used and the results obtained appear from the following tables. Table 1 Collector Designation Dimethyl dicocoalkyl ammonium chloride I a N-tallow alkyl-1, 3-diamine propane di¬ acetate I b Monotallow alkylamine + 15 EO II a Monotallow alkylamine + 50 EO II b Monococoalkylamine + 5 EO III a Monococoalkylamine + 11 EO III b _ Monococoalkylamine + 17 EO III c Monotallow alkyldiaminopropane + 10 EO IV a Monotallow alkyldiaminopropane + 20 EO IV b Monotallow alkyldiaminopropane + 30 EO IV c Monotallow alkyldiaminopropane + 40 EO IV d Table 2 Collector 1 Collector 2 Acid Calcite Test insoluble yield Type g/tonne Type g/tonne matter o o. o o A I a 350 - - 0.32 97.5 B I b 87.5 II b 262.7 0.24 87.8 C I b 175 II b 175 0.18 94.1 D I b 262.7 II b 87.5 0.12 84.2 E - - II b 350 1.34 96.9 F I a 175 II b 175 0.47 97.7 G I a 245 II b 105 0.30 98.0 H I a 280 II b 70 0.20 97.8 I I a 450 - - 0.15 96.8 1 I a 360 II a 90 0.09 98.2 1) 2 I a 360 III a 90 0.08 97.4 1) 3 I a 360 III b 90 0.06 97.8 1) 4 I a 360 III c 90 0.06 97.7 1) 5 I a 360 IV a 90 0:12 98. C 1) 6 I a 360 IV b 90 0.08 98. 1) 7 I a 360 IV c 90 0.06 98.2 1) 8 I a 360 IV d 90 0.03 97.6 1) 1) In tests 1-8, the calcite yield is calculated at 0.20% acid-insoluble matter. From these results appears that the flotation tests according to the invention, i.e. tests 1-8, gave a con¬ siderably lower content of acid-insoluble matter and, at the same content of acid-insoluble matter, a higher cal¬ cite yield than the prior-art techniσue and reference samples.

Claims: CLAIMS 1. A method of cleaning calcium carbonate ore con- taining silicate impurities, in which a froth-flotation process is performed in the presence of a cationic col¬ lector, c h a r a c t e r i s e d in that the collec¬ tor is a combination of a quaternary ammonium compound having the formula wherein one or two of the groups R]_, R 2 , R3 and R4 are a hydrocarbon group having 8-36 carbon atoms and the re- maining groups a hydrocarbon group having 1-7 carbon atoms or a hydroxyalkyl group having 2-7 carbon atoms and A is an anionic counterion, and an alkylene oxide adduct having the formula R5 wherein R5 is a hydrocarbon group having 8-22 carbon atoms, A]_, A and A3 are an alkylene oxide group having 2-4 carbon atoms, Rg is an alkylene group having 2-3 carbon atoms, n]_, n 2 and n 3 are 3-20 and the sum of all n , n and n is 10-40, and s is 0-3, the weight ratio of the quaternary ammonium compound to the alkylene oxide adduct being 3:2-11:1, and that calcium carbonate is recovered from the remainder, while contaminating silicates are removed with the float. 2. A method as claimed in claim 1, c h a r a c ¬ t e r i s e d in that two of the groups R]_, R 2 , R3 and R4 are hydrocarbon groups having 8-22 carbon atoms, pre¬ ferably 10-16 carbon atoms, while the two remaining groups are alkyl groups having 1-3 carbon atoms or hydroxyalkyl groups having 2-3 carbon atoms. 3. A method as claimed in claim 2, c h a r a c ¬ t e r i s e d in that the quaternary ammonium compound is a dimethyl dicocoalkyl ammonium salt. 4. A method as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that R5 is an alkyl group having 10-20 carbon atoms and that the sum of n , n 2 and n 3 is 12-30. 5. A method as claimed in any one of claims 1-4, c h a r a c t e r i s e d in that 70-100% of all alkyleneoxy groups in the alkylene oxide adduct are ethyleneoxy groups and 0-30% propyleneoxy groups. 6. A method as claimed in claims 1-5, c h a ¬ r a c t e r i s e d in that s is 0 or 1. 7. A flotation reagent, c h a r a c t e r i s e d in that it contains a quaternary ammonium compound ha¬ ving the formula R l-. + .- R 3 " ^ N ^ A- (I) R 2 ^ - R 4 wherein one or two of the groups R]_, R 2 , R3 and R4 are a hydrocarbon group having 8-36 carbon atoms and the re¬ maining groups a hydrocarbon group having 1-7 carbon atoms or a hydroxyalkyl group having 2-7 carbon atoms and A is an anionic counterion, in combination with an alkylene oxid adduct having the formula (A!)nχH (A 2 )n 2 H R 5 -(N R β ) s N (A 3 )n 3 H (II) wherein R5 is a hydrocarbon group having 8-22 carbon atoms, A_, A 2 and A3 are an alkylene oxide group having 2-4 carbon atoms, Rg is an alkylene group having 2-3 carbon atoms, nη_, n and n3 are 3-20, the sum of all τι \ , n 2 and n being 10-40, and s being 0-3, the weight ratio of the quaternary ammonium compound to the alkylene oxide adduct being 3:2-11:1, 8. A flotation reagent as claimed in claim 7, c h a r a c t e r i s e d in that two of the groups R^, R , R3 and R4 are hydrocarbon groups having 3-22 carbon atoms, preferably 10-16 carbon atoms, while the two re¬ maining groups are alkyl groups having 1-3 carbon atoms or hydroxyalkyl groups having 2-3 carbon atoms. 9. A flotation reagent as claimed in claim 7 or 8, c h a r a c t e r i s e d in that R5 is an alkyl group having 10-20 carbon atoms and that sum of n]_, n 2 and n3 is 12-30. 10. A flotation reagent as claimed in any one of claims 7-9, c h a r a c t e r i s e d in that 70-100% of all alkyleneoxy groups in the alkylene oxide adduct are ethyleneoxy groups and 0-30% propyleneoxy groups.

Inventors: KLINGBERG ANDERS, OLSSON LISBETH, KLINGBERG, ANDERS, OLSSON, LISBETH
Applicants: BEROL NOBEL AB, KLINGBERG ANDERS, OLSSON LISBETH, KLINGBERG, ANDERS, OLSSON, LISBETH
Application year: 1994
Main classification: B03D1
IPC codes: B03D1, C09K3